An industry-backed foundation has been putting out that message, with Stewart as a celebrity spokesman, but it’s not based on sound science. No major medical organization recommends mass screening for thyroid cancer.
Now, the U.S. Preventive Services Task Force has added its forceful voice to the mix. The federal oversight group puts thyroid cancer screening in its don’t-do-it category, in recommendations published in the Journal of the American Medical Association on Tuesday.
“The harms outweigh the benefits,” task force member Dr. Seth Landefeld says. “We would recommend against screening for thyroid cancer in adults who have no symptoms.” Landefeld is chairman of the Department of Medicine at the University of Alabama, Birmingham.
Screening for cancer would seem to be an obvious way to save lives, and often it is, but in this case screening efforts actually backfire, the task force concluded. The screening process almost always detects cancers that would never grow into life-threatening tumors.
“If you look early, you just find a whole new category of patients that has the disease but is never going to suffer from it at all,” says Dr. H. Gilbert Welch at the Dartmouth Institute for Health Policy and Clinical Practice. “But they will suffer from the treatment.”
Once growths are discovered, surgeons almost always remove the patient’s thyroid gland.
The surgery can have significant side-effects. Surgeons can sever the nerves that help control swallowing and speech, or remove the parathyroid gland, which regulates calcium. Patients go on a lifelong prescription of thyroid hormone.
“South Korea is the poster child for the problem of overdiagnosis” of thyroid cancer, Welch says. About 15 years ago, doctors there started a mass campaign to screen for thyroid cancer. That vastly increased the rate of thyroid cancer, to the point that it exceeded cases of breast cancer and other common malignancies.
Yet Welch notes that the mortality rate from this cancer didn’t change at all. “So all these extra cases were cases of thyroid cancer that weren’t destined to bother people,” he said. Instead, that rash of overdiagnosis sent people into needless surgery.
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Overdiagnosis Could Be Behind Jump In Thyroid Cancer Cases
Welch wrote an editorial about the dangers of overdiagnosis in JAMA Internal Medicine, which accompanies the task force recommendation.
Thyroid cancer rates have also been climbing in the U.S. since the 1990s, but as in South Korea, mortality rates have stayed flat. That’s a sign that doctors are identifying and treating cancers that didn’t need to be treated.
Harmless thyroid tumors are surprisingly common. Decades ago, pathologists in Finland noticed that more than a third of the people they saw in autopsy had thyroid tumors, but the cancers had no negative consequences.
“It’s different from the way we generally think about cancer,” Landefeld says. “The common conception is every cancer is going to grow until it’s stopped or removed or kills you. That is not the case with these cancers.”
Thyroid cancer is generally quite treatable and most people survive. The rarer forms of the cancer, which can be somewhat more dangerous, are not typically detected through screening of healthy people, Landefeld says.
The time to be concerned about thyroid cancer is at the first sign of symptoms.
“As soon as somebody has symptoms, such as a swelling in the neck or change in their voice or swallowing, or pain in the neck … you’re in a different ballpark,” Landefeld says. “You really want to sort those symptoms out.”
The foundation that promotes screening for thyroid cancer didn’t respond immediately to NPR’s request for comment.
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